Currently, most of the biochips are used to carry out biochemical analysis reactions or some part of the reactions. Compared to conventional analytical methods, biochips have the advantages of easy to operate, requiring less sample volume, allowing different reactions to take place at the same time, mass-producible, quick reaction speed, etc. A microfluidic device is one of many forms that implement the biochips. In a microfluidic device, channels, reaction chambers, mixers, and valves are provided on a substrate thereof to control flowing direction, reaction time, mixing ratio, etc. of different fluids on a chip, so as to achieve the purpose of controlling the reaction process. However, when a solution with a relatively high molecular weight solutes is supplied into the microfluidic device, the solutes diffuse in the channel at a relatively slow speed and accordingly, a relatively long sensing signal readout time is needed. Therefore, it is important to develop a way to speed up the migration of the solutes in the channels on a microfluidic device.